Pressure fluid operated pressure intensifier



sept. 28, 194s. E. R, PICE 2,450,160

PRESSURE FLUID OPERATED PRESSURE INTENSIFIER Filed April 19, 1944 Patented Sept. 28, l1948 PRESSURE FLUID OPEBATED PRESSURE INTENSIFIEB Earl lt. Price, South Bend, Ind., aaaignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application April 19, 1944, Serial No. 581,721

3 Claims. l

'I'his invention relates to a pressure fluid operated pressure intensiiler which is operated con-'- jointly by manually created pressure and power created pressure. More particularly, it relates to a booster for a hydraulic pressure system having a master cylinder and a motor, said booster being interposed in the connecting lines between said master cylinder and motor and comprising a diiferential air pressure power device and a second master cylinder which is adapted to build pressure in the motor and which itself is operated conjointly by the pressure of the differential air pressure power device and by the manually created pressure of the hydraulic liquid in the first master cylinder.

A recently proposed booster device incorporating the features mentioned in the preceding paragraph is characterized by the provision of coaxial relatively movable piston or plunger members in the aforesaid second master cylinder. In this arrangement an annular plunger is driven by the differential air pressure power device, while a second plunger has a portion extending inside the annular plunger just referred to and a portion at the rear which is subjected to the pressure of the manually operated master cylinder. The pressure of the latter plunger, which is subjected to manuallyl created pressure, aids the annular plunger in creating pressure in the motor, and control of the differential air pressure power device is accomplished by relative axial movements of the two plungers.

The device discussed in the preceding parai graph. in its present form, has several operating defects which must be remedied in order to provide a practical device. One of these defects is the tendency of the plungers or pistons to bind or stick in applied position, making it impossible to release the pressure in I,the motor. If this motor is operating brakes as contemplated, inability to release the pressure is a serious matter. A second important defect of this device is its occasional failure to obtain any power from the differential air pressure power device, due to its occasionally moving to full displacement without obtaining any greater pressure than that produced manually, even though the power device is fully operative. The latter trouble usually occurs on a slow application of pressure to the system.

The primary object of the present invention is to remedy the aforementioned defects in boosters of the type under discussion.

A second and related object is to remedy said (ci. xo-ses) defects without adding substantially to the complexity or expensiveness of the booster.

Other objects and advantages of the present invention will become apparent during the course s of the following description, reference being had therein to the accompanying drawing, in which:

Figure l is a vertical sectional view taken through a fluid pressure booster incorporating my invention; and

Figure 2 is a closeup of a portion o l the fluid pressure booster of Figure i.

Referring to the drawing, it shows the combination of a power device, a control for the power device and a master cylinder operated by ll the power device. The master cylinder of the power unit or booster comprises two aligned coaxial portions i2 and I4. The portion i2 has a cylindrical bore it which communicates through a port il with a conduit leading to a manually -opex'alzile conventional master cylinder 2i. The portion Il has a cylindrical bore 22 which communicates by means of a port 24 with conduit 2G leading to the motor or motors which are to be operated, such as the wheel cylinders 21 of SB a hydraulically applied brake. The portion I2 of the master cylinder ls mounted on a shell 28 constituting one side of a differential air pressure power device. The portion il of the master cylinder is mounted on a shell 30 constituting the 30, other side of the din'erential air pressure power device. Clamped between the shells 2l and 30 is an annular flexible diaphragm 22 which is retained at its inner end in a piston 34, the piston being directly mechanically connected with an annular plunger 3l to drive the same into the bore 22 to create brake applying pressure. The pressure created in the manually operated conventional master cylinder acts against the enlarged left end $8 of the piston III which extends 40 through the differential air pressure power device and has a forward or head portion 42 inside the annular plunger It and acting in the bore 22 of the master cylinder. The pressure created in bore 22 thus results from the combined pressure of the piston Il and the hydraulic pressure acting against the portion Il of piston 40. The operator is apprised of the amount of powercreated pressure in chamber 22 by the reaction of that pressure against the forward end 42 of 60 piston Il, the ratio of reaction to total brake applying pressure being equal to the ratio of areas of the smaller forward end 42 of piston lli to the larger rearward end 32 of the same piston.

55 Operation of the dierential air pressure 3 power device is controlled by valves, which are in turn controlled by relative movements oi'piston 40 and plunger II. A relatively low pressure source. such as the intake manifold ot an automobile. is connected by means of pipe Il to chamber 4I of the power device, which is formed between the piston ll and shell Il. A relatively high pressure source. such as Ithe atmosphere. or compressed air, is connected by means of pipe Il to a flexible tube il which is supported by the iioats with the diaphragm and piston assembly 22-24. The operation of the power device depende upon the pressure in chamber l2, which is between piston 24 and shell 2l. Two valve elements are adapted to control the pressure in chamber l2. One of these valve elements. indicated at Il. controls the communication of chamber l2 with the low pressure source, while the other valve element, indicated at It. controls the communication of chamber 52 with the high pressure source. A floating valve actuating member Il is adapted to be moved by piston Il to operate the valve elements Il and 5t.

In order that the hydraulic iluid in chamber 22 and in the motors which are connected thereto may be in direct communication with hydraulic iluld in chamber It and in the manually operable master cylinder so long as the brakes are released, thus providing that compensation for changes in the volume of the hydraulic iluid may be accompllshed by means of a single reservoir which is provided as a part of the conventional master cylinder 2| ,-a passage l0 extends longitudinally through: piston 4l. Since iluid communication between chambers Il and 22 must be cut oil! during brake application, a check valve I2 is adapted to seat against ilange Il inside passage In to cut on the flow of liquid from chamber It to 22 as soon as piston 4l has moved to the right sumciently-ior the rod M, which holds valve 82 away f from flange Il when piston Ill is in its retracted position. to permit valve 62 to seat.

During the applying stroke of piston and plunger 2l, it is necessary that the valve member l2 move to closed position and cut oil communication between chambers IG and 22. l

Heretofore the pressure of fluid in chamber 2 2 has been relied on to'move valve member 82 to its seat after the pressure stroke of piston I0 has begun. This may have the purpose of permitting a relatively large flow of fluid from chamber I8 to chamber 22 before the displacement of the limited amount of fluid in chamber 22 begins.

' moving .the valve 62 to its seat immediately upon by positioning the cylinder on a vertical axis with the valve 02 above the piston 40.

Because the portions l2 and I4 of the master cylinder are formed as separate units andv separately mounted, manufacturing tolerances throughout the construction of the master cylinder itself and of the power device almost invariably result in a slight mlsalignment of the bores il and 22. This misalignment results 'in binding oi piston 40 in chamber I8, oi' plunger 2i in chamber 22, and particularly of the forward end 42 of piston 40 against the annular plunger 28. With forward or pressure applying -xnovement of the vpiston 40 in plunger 2t the binding therebetween increases, since the eil'ect of misalignment of the bores is a gradual increase in the original eccentrlcity as the plunger and piston move forward in the applying stroke.

The possibility of binding between piston 40 and plunger 36 is particularly important since it disturbs the action of the valve means which control the power device. The binding is greatest at the end of the stroke, and-consequently it tends to prevent the valve from releasing and to hold the brakes in applied position, regardless of the efforts of the operator to release them.

In order to-prevent binding between the piston 40 and plunger 26, relative movement of which is relied upon to control the valves El and 58, I limit the bearing surface between piston 40 and plunger 38 to the small surface 18 provided at the forward end of plunger 28. This bearing is in effect a pivotal bearing which permits the plunger 36 to move somewhat out of line with piston 40 asthey both move forward into chamber 22, without exerting an appreciable binding force tending to prevent movement of piston 40 relative to plunger 36. I thus insure that the valve which controls the power device will be fully controllable at all times, and that the binding force will never be sufficient to prevent release of the power and release of the brakes.

Although a particular. embodiment of my invention has been described, it will be understood `by those skilled in the art that the objects of the invention may be attained by the use of construc- V tions different in certain respects from that dis- However. it has been-found that, during certain brake applications, particularly those wherein the brake applying pressure is gradually augmented. chambers l0 and 22 remain in communication throughout the full pressure stroke, and therefore the entire brake applying pressure is built up manually, the power device being incapable of adding any pressure to ease the operators effort. I propose to prevent occurrences of this kind by providing suitable means for positively insurins that communicationl will be cut ofi' between chambers ii and 22, almost immediately upon the application of pressure by the operator to the manually operated master cylinder.

A positively acting resilient member such as the spring il is compressed between the ball valve member l2 and a shoulder 1li provided in the front end of passage Il by a ring which may be held in position by a C spring 'I2 snapped into a groove in the inner forward end of the piston. The exact structure may be varied somewhat but closed without departing from the underlying principles of the invention. I therefore desire by the following claims to include within the scope of my invention all such variations and modifications by which substantially the results of my invention may be obtained through the use of substantially the same or equivalent means.

I claim:

1. A device, for applying a combined power and manually created pressure to a hydraulic pressure system, having coaxial bores at opposite sides thereof, one connected to a manually operable hydraulic master cylinder and the other connected to a hydraulic motor, an annular plunger reciprocable in the motor-connected-bore, a poweroperated booster element operatively associated with the annular plunger to drive the same to build pressure in the motor, a stepped piston having a small diameter portion reciprocable in the annular plunger and a larger diameter portion reclprocable in the master-cylinder-connectedbore, the piston and plunger being in pivotal bearing relationship with one another whereby rela- 2. A device. ior 'applying a combined power vand manually created pressure to a hydraulic pressure system. having coaxial bores at opposite sides thereof. one connected to a manually operable hydraulic master cylinder and the other connected to a hydraulic motor. an annular plunger reciprocable in the motor-connectedbdl'e. a power-operated booster element operatively associated with the annular plunger to drive the same to build pressure in the motor. a stepped piston having a small diameter portion reciprocable in the annular plunger and a large diameter portion reciprocable in the mastercylinder-oonnected-bore. the piston and plunger being in pivotal bearing relationship with one another whereby relative angular movement of the piston and plunger is permitted in order to prevent binding. said stepped piston having a passage therethrough interconnecting the coaxial bores. a valve adapted to seat and thereby close the passage during the pressure stroke of the plunger and piston. and means for holding the lvalve unseated when the piston is in retracted position.

3. A device. for applying a combined power and manually created pressure to a hydraulic pressure system. having oo'aiial bores at opposite sides thereof. one to a manually operable hydraulic master cylinder and the other connected to a hydraulic motbr, an annular plunger reciprocable in the motor-connected-bore, a

power-operated booster element operatively associated with the annular plunger to drive the same to build pressure in the rmoton and a stepped piston having a small diameter portion extending through the annular plunger into the motor-connected-bore and a large diameter portion reciprocable in the mastercylinderconnectedbore, the small diameter end of the piston being supported by bearing contact with the plunger only at the forward end oi' said plunger, thereby permitting angular pivotal movement of the piston and plunger with respect to one another during their pressure stroke.

, EARL R. PRICE.

` Remmers crrxzn 'I'lxe following references are o! record in the tile of this patent:

UNITED STATES PATENTS o'rnm ons Commercial ACar Journal. Sept. 1943, page 64, (published by Chilton C0.. Philadelphia. Pa.) 

